Method of making radiator-tubes



R. 8. HOOKER.

METHOD 0F MAKING RADIATQR TUB ES. APPLICATION FILED SEPT! 24, 1918.

L368Al D Patented Dec. 28, 1920.

Llllillllllllihilllllllllfi n stares renew ME'IHQD OF MAKING RADIATOR-TUBES.

Specification of Letters Patent.

Patented Dec. as, time.

Application filed September 24:, 1918. Serial No. 255,4:92.

To all whom it may concern:

Be it known that 1, Ross B. HOOKER, a citizen of the United States residing at Lowell, in the county ,of iddlesex and State of Massachusetts, have invented new and useful Improvements in Methods of Making Radiator-Tubes, of which the following is a specification. I v

This invention relates to the manufacture of seamless tubes for use in the radiators of automobiles and aeroplane motors.

In honeycomb radiators, built up of a multiplicity of open-ended, thin-walled tubes with their .ends hermetically secured together and their bodies of slightly reduced size to form Water passages, it is highly desirable that the radiator be of as light weight as possible and afford as large radiating or heat-transmitting surface as possible, so that the hot water from the engine jacket may be forced to give up a large quantity of its heat during its passage around the air-traversed radiator tubes.

In radiators of this type, the hot water from the jacket enters at the top of the radiator and filters down over and among the tubes of the honeycomb, returning to the jacket from the bottom of the radiator. Such radiators have heretofore been built up of tubes with their ends enlarged, relatively to their bodies, and secured together by soldering, the spaces between the bodies constituting a devious passageway for the water to be cooled. It has also been proposed to form longitudinal grooves or corrugations in the bodies of the tubes for the purpose of increasing the area of the heat transferring or radiating surface.

For a number of years past, I have been manufacturing radiator tubes from seamless extruded tubes made according to the processes claimed in the patent to George W. Lee, No. 822,285, and L. E. Hooker, No. 922,585, and b the machine claimed in the patent to L. Hooker, No. 918,154. In

order to obtain the necessary water space, of

from 0.04 to 0.05 of aninch, between the tubes, the praoticehas-been to surround the ends of the tubes with a #14: gage brass wire. I have also attempted to obviate the use of this wire by expanding the ends of the tubes into hexagonal or square shape,

but encountered the difficulty that a large percentage of the'tubes would split at the corners,on account of the extreme thinness of the metal, (approximately 0.005 of an inch). I then experimented by contracting the bodies of the tubes and pressing their ends into hexagonal shape without expand- 1ng them beyond the original diameter of the tube, which has proved to be a practical method.

I have also made a further improvement in the construction of these tubes, which consists in spirally corrugating them as they come from the extruding machines, then cutt ng them up into lengths suitable for use 1n the radiators, and finally die-shaping the ends into polygonal form, preferably hexagonal. In this way, the metal is enabled to withstand the expansion, since the diameter of the extruded tube is first reduced throughout its length by being drawn through the corrugating die, and the ends are only expanded to about the original diameter of the tubes, that is to say, the ends become hexagons (or squares) of the size of that hexagon or square which can be in scribed in the circle represented by the original diameter of the extruded tube, or of that which can be circumscribed on the circle of the reduced corrugated tube, the essential being that the metal at the endsof comb and is caused to travel over a greater surface area than it would if the tube surrents encounter obstacles in passin through the tubes, whereby the area of the aircooled surface is also increased. The tubes are also strengthened by the corrugating and. as stated, the metal of the ends is not unduly strained.

The invention is illustrated in the accompanying drawing, in which Figure 1 is an end view of the extruded tube after it has been drawn through the reducing and corrugating die, the circumference of the original extruded tube being shown in dotted lines. Fig. 2 is a side elevation of the corrugated tube cut to the length of the radiator tube. Fig. 3 is an end elevation of the expanded hexagonal end of the radiator tube, the'circumference of the original extruded tube being shown .faces were smooth, and also that the air curof the completed radiator tube, and Fig. 5

is an elevation of a plurality of such tubes assembled into a radiator section.

In these views, the dotted circle 1, in Figs. 1 and 3, represent the tube as it comes from the extruding machine; this extruded tube has its lower end closed, is smoothly cylindrical throughout with a wall of about 0.005 inch thickness, and is from 16 to 20 inches long.

2 represents said tube after it has been simultaneously reduced in diameter and spirally corrugated at 3, by passing it through a spirally fluted die, and after it has been cut up into lengths suitable for the radiator.

4 represents the ends of said tubes after they have been re-expanded in a die into hexagonal shape. It will be understood that the shape of the endsmay be other than a hexagon, if desired, and that the expansion is such that the dia onals between opposite salient angles of the hexagon, or other polygon, are not materially longer than the diameter of the original extruded tube 1. The reexpanded ends may be circular, if desired, but, in that case, the spaces between the tangent circles would have to I be filled up by some means, whereas, with polygonal ends, no fillers or headers are necessary, since they present flat faces which are soldered together.

5, in Fig. 5, represents, as stated, a section of a radiator core composed of tubes made as above described, the adjacent sides of the hexagonal ends having been soldered together. It will be seen that the spiral corrugations of the-adjacent tubes run in opposite directions, that is, cross each other, the consequence of which is that the water, in percolating through the core, is caused to take a diagonal path, that is, to follow diagonal passages formed by the corrugations.

This effect, which is, of course, not-present when the tubes are plain or smooth or have I straight corrugations or grooves, of the water being obliged to flow partially longitudinally of the tubes as well as transversely thereto greatly augments the cooling" action. Ilecently I had two radiators built in this way, tested at the laboratory of Yale University and the report shows that greater cooling efficiency was obtained than was the case with any other radiator previously tested there, even than with the Mercedes square tube type of radiator, of which I have built a large number and which I have heretofore considered as possessing the greatestcooling efliciency of any type of radiator embodying an equal amount of metal invention,

drical tube of considerable length, passing it through a drawing die which spirally corrugates its wall, cuttin it up into suitable lengths, and reexpan ing its ends into polygonal shape having a diagonal dimension not exceeding the diameter of the original extruded tube.

2. The method of making a radiator tube, which consists in spirally corrugating a seamless tube, and then expanding its ends for an amount not greater than the diameter of the original seamless tube.

3. The method of making a radiator tube, which consists in taking a longseamless tube, drawing it down and at the same time spirally corrugating it throughout its length, cuttin it up into radiator tube lengths. and ie-shaping its ends into the form of a hexagon which can be inscribed in a circle of the diameter of the original seamless tube.

4. The method of making a radiator tube, which consists in extruding a seamless tube of considerable length and cylindrical throughout its length, reducing its diameter and increasing its length by drawing, outtin it up into the length of a radiator tube, an rexpanding its ends to a polygonal shape, the greatest diagonal dimension of which does not exceed in length the diameter of said extruded tube.

In testimony whereof I have hereunto set my hand.

ROSS B. HOOKER. 

